1. Field of the Invention
The present invention relates to an orientation detection device, an orientation detection method and a program storage medium.
2. Description of the Related Art
Conventionally, a musical performance device has been proposed which detects the playing motion of an instrument player and emits a sound corresponding to the playing motion. For example, a musical performance device is known which emits a percussion sound with a structure only including a drumstick-shaped member. In this musical performance device, a sensor is provided to its drumstick-shaped member. When the instrument player holds and swings the member by hand, the sensor detects the playing motion, and a percussion sound is emitted.
With this virtual musical performance device, a musical sound of a musical instrument can be emitted without requiring a real musical instrument, and therefore the instrument player can enjoy playing without restriction on a playing place or a playing space.
As a virtual musical performance device as described above, for example, Japanese Patent Application Laid-Open (Kokai) Publication No. 2007-256736 discloses a musical performance device which is structured such that an acceleration sensor is provided to a drumstick-shaped member, and emits a musical sound after an output (an acceleration value) obtained from the acceleration sensor by shaking the member reaches a predetermined threshold.
Meanwhile, in the virtual musical performance device, a different musical sound is often provided for each different playing motion of an instrument player. Also in the configuration of the musical performance device disclosed in Japanese Patent Application Laid-Open (Kokai) Publication No. 2007-256736, a geomagnetic sensor is used to determine the orientation of the drumstick-shaped member and a musical sound of a different timbre can be emitted according to the orientation. In this case, however, since a sound source can be placed only in a horizontal direction, the maximum number of sound sources is three or four, and sound sources more than this cannot be placed.
As a method of solving this problem, sound sources can be placed according to an angle with respect to a gravity direction by using an acceleration sensor. Although gravity can be sensed by the acceleration sensor, gravity is combined with an external force to become a resultant force, and therefore the gravity direction cannot be specified when the drumstick is moved at high speed. Thus, accuracy of drumstick orientation estimation is degraded.